<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, user-scalable=no, minimum-scale=1.0, maximum-scale=1.0">
    <title>Demo1-简单场景</title>

    <style>
        body {
            margin: 0;
            text-align: center;
        }

        #info {
            position: absolute;
            top: 0;
            width: 100%;
            padding: 10px;
        }

    </style>

    <script src="js/three.js"></script>
    <script src="js/libs/ammo.js"></script>
    <script src="js/controls/OrbitControls.js"></script>
    <script src="js/libs/stats.min.js"></script>
    <script src="js/Detector.js"></script>
</head>
<body>

<div id="container"><br /><br /><br /><br /><br />Loading...</div>
<div id="info">Demo1 - 简单场景,物块坠落</div>

</body>

<script>
    // 检测浏览器是否支持webgl
    if (!Detector.webgl) {
        Detector.addGetWebGLMessage();
        document.getElementById('container').innerHTML = '';
    }

    // 全局变量

    // 绘图相关变量
    var container, stats;
    var camera, controls, scene, renderer;
    var textureLoader;
    var clock = new THREE.Clock();

    // 物理引擎相关变量
    var gravityConstant = -9.8;
    var collisionConfiguration;
    var dispatcher;
    var broadphase;
    var solver;
    var physicsWorld;
    var rigidBodies = [];
    var margin = 0.05;
    var transformAux1 = new Ammo.btTransform();

    //
    var time = 0;

    // 鼠标输入相关
    var mouseCoords = new THREE.Vector2();
    var raycaster = new THREE.Raycaster();
    var ballMaterial = new THREE.MeshPhongMaterial( { color: 0x202020 } );

    // - 主程序
    init();
    animate();


    // -函数定义
    function init() {
        initGraphics();

        initPhysics();

        createObjects();

        initInput();
    }

    function initGraphics() {
        // three.js基本场景配置
        container = document.getElementById('container');
        container.innerHTML = "";

        camera = new THREE.PerspectiveCamera(60, window.innerWidth/window.innerHeight, 0.1, 2000);
        camera.position.x = -7;
        camera.position.y = 5;
        camera.position.z = 8;

        controls = new THREE.OrbitControls(camera);
        controls.target.y = 2;

        renderer = new THREE.WebGLRenderer();
        renderer.setClearColor( 0xbfd1e5 );
        renderer.setPixelRatio(window.devicePixelRatio);
        renderer.setSize(window.innerWidth, window.innerHeight);
        renderer.shadowMap.enabled = true;

        textureLoader = new THREE.TextureLoader();

        // 场景
        scene = new THREE.Scene();

        // 环境光
        var ambientLight = new THREE.AmbientLight(0x404040);
        scene.add(ambientLight);

        // 线性光
        var light = new THREE.DirectionalLight(0xffffff, 1);
        light.position.set(-10, 10, 5);
        light.castShadow = true;
        var d = 10;
        light.shadow.camera.left = -d;
        light.shadow.camera.right = d;
        light.shadow.camera.top = d;
        light.shadow.camera.bottom = -d;

        light.shadow.camera.near = 2;
        light.shadow.camera.far = 2;

        light.shadow.mapSize.x = 1024;
        light.shadow.mapSize.y = 1024;

        scene.add(light);

        container.appendChild(renderer.domElement);

        // 显示帧数
        stats = new Stats();
        stats.domElement.style.position = 'absolute';
        stats.domElement.style.top = 'absolute';
        container.appendChild(stats.domElement);

        // 添加窗口大小变化监听
        window.addEventListener('resize', onWindowResize, false);

    }

    function onWindowResize() {
        camera.aspect = window.innerWidth / window.innerHeight;
        camera.updateProjectionMatrix();

        renderer.setSize( window.innerWidth, window.innerHeight );

    }

    function initPhysics() {
        // bullet基本场景配置
        collisionConfiguration = new Ammo.btDefaultCollisionConfiguration();
        dispatcher = new Ammo.btCollisionDispatcher(collisionConfiguration);
        broadphase = new Ammo.btDbvtBroadphase();
        solver = new Ammo.btSequentialImpulseConstraintSolver();
        physicsWorld = new Ammo.btDiscreteDynamicsWorld(dispatcher, broadphase, solver, collisionConfiguration);
        physicsWorld.setGravity(new Ammo.btVector3(0, gravityConstant, 0));
    }

    function createObjects() {
        var pos = new THREE.Vector3();
        var quat = new THREE.Quaternion();

        // 创建地面
        pos.set(0, -0.5, 0);
        quat.set(0, 0, 0, 1);
        var ground = createParallellepiped(40, 1, 40, 0, pos, quat, new THREE.MeshPhongMaterial({color: 0xffffff}));
        ground.castShadow = true;       // 开启投影
        ground.receiveShadow = true;    // 接受阴影(可以在表面上显示阴影)
        textureLoader.load("./textures/grid.png", function (texture) {
            texture.wrapS = THREE.RepeatWrapping;
            texture.wrapT = THREE.RepeatWrapping;
            texture.repeat.set(40, 40);
            ground.material.map = texture;
            ground.material.needsUpdate = texture;
        });

        // 随机创建30个箱子
        for (var i = 0; i < 30; i++) {
            pos.set(Math.random(), 2 *i, Math.random());
            quat.set(0, 0, 0, 1);

            createParallellepiped(1, 1, 1, 1, pos, quat, createRendomColorObjectMeatrial());
        }
    }

    // 生成随机颜色材质
    function createRendomColorObjectMeatrial() {
        var color = Math.floor(Math.random() * (1 << 24));
        return new THREE.MeshPhongMaterial({color: color});
    }

    function createParallellepiped(sx, sy, sz, mass, pos, quat, material) {
        var threeObject = new THREE.Mesh(new THREE.BoxGeometry(sx, sy, sz, 1, 1, 1), material);
        var shape = new Ammo.btBoxShape(new Ammo.btVector3(sx * 0.5, sy * 0.5, sz * 0.5));
        shape.setMargin(margin);

        createRigidBody(threeObject, shape, mass, pos, quat);

        return threeObject;
    }

    function createRigidBody(threeObject, physicsShape, mass, pos, quat) {
        threeObject.position.copy(pos);
        threeObject.quaternion.copy(quat);

        var transform = new Ammo.btTransform();
        transform.setIdentity();
        transform.setOrigin(new Ammo.btVector3(pos.x, pos.y, pos.z));
        transform.setRotation(new Ammo.btQuaternion(quat.x, quat.y, quat.z, quat.w));
        var motionState = new Ammo.btDefaultMotionState(transform);

        var localInertia = new Ammo.btVector3(0, 0, 0);
        physicsShape.calculateLocalInertia(mass, localInertia);

        var rbInfo = new Ammo.btRigidBodyConstructionInfo(mass, motionState, physicsShape, localInertia);
        var body = new Ammo.btRigidBody(rbInfo);

        threeObject.userData.physicsBody = body;

        scene.add(threeObject);

        if (mass > 0) {
            rigidBodies.push(threeObject);

            // Disable deactivation
            // 防止物体弹力过快消失

            // Ammo.DISABLE_DEACTIVATION = 4
            body.setActivationState(4);
        }

        physicsWorld.addRigidBody(body);

        return body;
    }

    function animate() {
        requestAnimationFrame(animate);

        render();

        stats.update();

    }

    function render() {
        var deltaTime = clock.getDelta();

        updatePhysics(deltaTime);

        controls.update(deltaTime);

        renderer.render(scene, camera);

        time += deltaTime;
    }

    function updatePhysics(deltaTime) {
        physicsWorld.stepSimulation(deltaTime);

        // 更新物体位置
        for (var i = 0, iL = rigidBodies.length; i <iL; i++ ){
            var objThree = rigidBodies[i];
            var objPhys = objThree.userData.physicsBody;
            var ms = objPhys.getMotionState();
            if (ms) {
                ms.getWorldTransform(transformAux1);
                var p = transformAux1.getOrigin();
                var q = transformAux1.getRotation();
                objThree.position.set(p.x(), p.y(), p.z());
                objThree.quaternion.set(q.x(), q.y(), q.z(), q.w());
            }
        }
    }

    function initInput() {

        window.addEventListener( 'mousedown', function( event ) {

            mouseCoords.set(
                    ( event.clientX / window.innerWidth ) * 2 - 1,
                    - ( event.clientY / window.innerHeight ) * 2 + 1
            );

            raycaster.setFromCamera( mouseCoords, camera );

            // Creates a ball and throws it
            var ballMass = 35;
            var ballRadius = 0.4;

            var ball = new THREE.Mesh( new THREE.SphereGeometry( ballRadius, 14, 10 ), ballMaterial );
            ball.castShadow = true;
            ball.receiveShadow = true;
            var ballShape = new Ammo.btSphereShape( ballRadius );
            ballShape.setMargin( margin );
            var pos = new THREE.Vector3();
            var quat = new THREE.Quaternion();
            pos.copy( raycaster.ray.direction );
            pos.add( raycaster.ray.origin );
            quat.set( 0, 0, 0, 1 );
            var ballBody = createRigidBody( ball, ballShape, ballMass, pos, quat );

            pos.copy( raycaster.ray.direction );
            pos.multiplyScalar( 24 );
            ballBody.setLinearVelocity( new Ammo.btVector3( pos.x, pos.y, pos.z ) );

        }, false );

    }


</script>

</html>